216 



Mr. Harvey on Square and 



The first column indicates the lines of fire which intersect each 

 other; the second contains the magnitudes of the ordinates repre- 

 senting the distances of the points of cross-fire, from the principal 

 axis X Y ; and the third, the distances of the ordinates estimated 

 on the principal axis, from the common point of origin K. To refer 

 for example, the point of intersection produced by the lines of 

 cross-fire B b and C c to the axis X Y, it will be found, that the 

 ordinate n G = 18. 2 feet, and the ordinate G K = 6. 2 feet. So 

 also, for the point of intersection of B b and L I, we have the ordi- 

 nate Ih^ 19. 5 feet, and L K = 8. feet. 



